Devices of the mentioned type are described in German Patent No. 22 24 407 (which corresponds to British Patent No. 1389746) and U.S. Pat. No. 3 850 780. They have an advantageous mechanism which effects a movement of two sealing jaws in closed cam guideways so that they clamp the foil material between one another over and as long as possible rectilinear distance without necessitating a lowering of the running speed for the purpose of a secure sealing of the foil material, which material is more difficult to process.
However, problems result during packaging of particularly bulky fill material, which can often involve considerable variances in volume during feeding and filling in spite of an even amount or weight dosing. For example, potato chips by all means do not have a uniform size, alone because even with a good grading significant potato-size variations can occur. Chips manufactured from freshly harvested potatoes can therefore possibly be above average in size, thus may be bulky; after a longer storage period, the dimensions are generally less due to shrinkage caused by a loss of moisture. On the other hand, the package size is often fixedly predescribed, for example by rigid foil processing measurements, by specific imprint patterns and the like, so that in automatic packaging systems difficulties during the sequence of operation were unavoidable up to now.
In view of this need, the purpose of the invention is to provide a device of the above-mentioned type wherein the automatic packaging of particularly bulky fill material can occur without any breakdown due to the processing of different individual volumes and wherein uniform package sizes are reliably assured through economic means.
According to the invention, compressing members are each forcedly arranged in front of the sealing jaws. Thus, it is achieved in a surprisingly simple manner that the volume of bulky fill material is compared in each case prior to the start of the sealing operation. The fill material is, at least in the area of the subsequent sealing surface, broken and moved into the bag at this area. The compressing members have a relative speed with respect to the package. A certain compressing of the fill volume is effected in the package which is being created due to the compressing members being moved toward one another in front of the sealing jaws and moving the bulky product parts into the package being created. Thus, the compressing members function as shaping tools, for which reason they can also be identified as roll compressors, strip slides, press rollers or the like. The inventive device is particularly also suited for fill material in which a crushed portion is basically tolerable. Bulky projecting product parts can thereby be crushed or broken by the compressing members or the shaping elements and moved farther into the package, so that the content is slightly compressed and the subsequent cross-sealing can occur without any problems at the pregiven area.
The compressing members are provided at the ends of the levers pivotally supported on the sealing-jaw carriers. Thus, one can utilize the conventional design of intermittently operating bagging machines of the above-mentioned type, with the sealing-jaw carriers carrying cut through pulling combined swivelling and lifting movements. Also such devices can be easily equipped with the inventive compressing members which, so to speak, ride with their levers on the sealing-jaw carriers. The length of the compressing members is preferably substantially equal to the length of the sealing jaws. It is very advantageous from a technical manufacturing standpoint, if the compressing members are constructed cylindrically, for example as circular rods, rollers, cage bars or the like, so that manufacture and installation are done in a particularly simple manner.
An advantageous design of the invention consists in the compressing members being spring loaded with respect to the sealing jaws and being relatively movable under the spring force. Tension springs can for this purpose be provided, which tension springs are each arranged between arms of the sealing jaws and the other ends of the levers. The latter can be dimensioned such that they can be swung on both sides of the sealing jaws passed their front edge. Important is the compressing members leading the sealing jaws such that the relationship between compressing-member distance (the area during which the foil is clamped) to the active sealing-jaw width is in any case greater than 1, preferably greater than 3.
A structurally particularly advantageous design exists if rollers are associated on both sides with the compressing members, which rollers roll along on or in a path of a guide member, which path extends transversely with respect to the plane of symmetry.